Efficacy and Economics of Summer Fallow Conventional and Reduced-Tillage Programs for Sugarcane

Abstract

During the summer fallow period of the sugarcane production cycle, glyphosate in conjunction with frequent tillage is used to destroy sugarcane regrowth and reduce perennial weed infestations. For tillage to be reduced or eliminated in fallowed fields, weed control must be maintained and sugarcane must be completely destroyed so as not to interfere with the subsequent planting operation. Field studies were conducted to evaluate glyphosate rates and formulations for control of sugarcane, bermudagrass, and johnsongrass. Glyphosate (isopropylamine salt) applied in April at 1.68, 2.24, and 2.80 kg ai/ha controlled 15-cm sugarcane at least 95% 42 d after treatment (DAT). Control of 25- and 40-cm sugarcane was maximized at 1.68 kg/ha (91 and 86% control, respectively). In another study, 25-cm sugarcane was controlled equally with isopropyl amine and potassium salt glyphosate formulations. Bermudagrass control 40 d after glyphosate was applied at 1.12 kg/ha was 86% and increased to 98% when the same rate was applied sequentially. In fallowed sugarcane fields, conventional-tillage, reduced-tillage, and no-tillage programs were implemented from mid-April through mid-August to evaluate weed control and economics. When a glyphosate application was substituted for a tillage operation, bermudagrass and johnsongrass control was increased compared with the conventional tillage alone program, but differences in sugarcane and sugar yield among the various programs the following year were not observed. Based on 2006 costs, elimination of a single tillage operation reduced cost $18.49/ha and addition of glyphosate (2.8 kg/ha plus application cost) increased cost $43.47/ha. Total cost for the conventional tillage–alone fallow program was $110.94/ha; where herbicide was used in the reduced-tillage and no-tillage programs, total cost was $19.47 to $77.38/ha more.

Weed Management in Single- vs. Twin-Row Cotton (Gossypium hirsutum)

“…Least square means were calculated and mean separation (P # 0.05) was produced using PDMIX800 in SAS, which is a macro for converting mean separation output to letter groupings (Saxton 1998). This statistical approach has been used successfully in previous research findings (Bond et al 2007(Bond et al , 2008(Bond et al , 2009Etheredge et al 2009;Leon et al 2008;Levy et al 2006;Walker et al 2008;Webster et al 2007). Analysis of cotton injury and weed control excluded the nontreated checks, but nontreated plot data were included in the yield and IPAR analyses.…”

Reducing the Risks of Herbicide Resistance: Best Management Practices and Recommendations

“…When combined with proper timing of herbicide application, tillage or cultivation can effectively control perennial weeds such as bermudagrass [Cynodon dactylon (L.) Pers.] (Etheredge et al 2009), johnsongrass (Bruff et al 1996), and redvine [Brunnichia ovata (Walt.) Shinners](Castello et al 1998).…”

Spring-applied triclopyr mixtures for bermudagrass (Cynodon dactylon) suppression in Louisiana sugarcane

“…No selective herbicides resulted in adequate bermudagrass injury without injuring sugarcane; therefore, the fallow period is an optimal time to reduce perennial weed infestations before sugarcane is replanted (Miller et al 1999;Richard 1997a). Following harvest of the final ratoon crop, some sugarcane is treated with 1.68 kg ha -1 of glyphosate to terminate the crop (Etheredge et al 2009). Fallowed fields treated with repeated glyphosate applications in combination with reduced or no tillage decreased November bermudagrass groundcover 81% to 95% when compared to cultivation alone in Louisiana (Etheredge et al 2009).…”